Non-cancerous tumours and conditions of the kidney

A non-cancerous (benign) tumour of the kidney is a growth that does not spread (metastasize) to other parts of the body. Non-cancerous tumours are not usually life-threatening. They are typically removed with surgery and do not usually come back (recur).

A non-cancerous condition of the kidney is a change to kidney cells, but it is not cancer. Non-cancerous conditions do not spread to other parts of the body and are not usually life-threatening.

There are various types of non-cancerous tumours and conditions of the kidney.

Non-cancerous tumours

Papillary renal adenoma

Papillary renal adenoma is the most common non-cancerous kidney tumour. These tumours are small, grow slowly and usually don’t cause any symptoms. They are often found during an imaging test done for other reasons.

Oncocytoma

Oncocytoma starts in the cells of the collecting ducts of the kidney. These tumours can grow quite large. There can be several oncocytomas in one or both kidneys. Oncocytomas may be found at the same time as a cancerous tumour.

Angiomyolipoma

Angiomyolipoma is a kidney tumour made up of fat, blood vessels and smooth muscle tissue. They often develop in people with tuberous sclerosis, a genetic condition that causes non-cancerous tumours to form in many organs, including the eyes, skin, brain, lungs, heart and kidneys. Even though these tumours are non-cancerous, they can spread into and destroy surrounding tissue. Tumours larger than 4 cm (1-1/2 in) can also cause sudden bleeding (called hemorrhage) from the kidney into the abdomen.

Treatments

Surgery is the main treatment for non-cancerous kidney tumours. Other treatment options include:

Non-cancerous conditions

Simple kidney cysts are the most common non-cancerous condition of the kidney. A simple cyst is a round or oval fluid-filled sac. One or more cysts can develop in a kidney. Simple kidney cysts are very common in people over the age of 50.

Most simple kidney cysts are found when an imaging test is done for other medical reasons. When seen on an imaging test, simple kidney cysts have smooth, well-defined and rounded edges. This helps doctors tell them apart from kidney tumours.

If simple kidney cysts are not causing any symptoms, they do not need any treatment. If they start causing problems (like pain, infection or bleeding) the doctor will drain the cysts using a long needle or have them removed by surgery.